Low styrene polystyrene-polyisoprene-polystyrene block copolymer, or copolymers with less than 25 weight percent styrene are known to yield useful pressure sensitive adhesives when used in combination with tackifier resins, plasticizer oil, and antioxidants. These adhesives are useful in a variety of applications such as tape and label applications which require good tack in addition to the ability to bond to a wide variety of low and high energy surfaces, e.g., paper, plastic films, and metals. It is very desirable to retain tack and low temperature flexibility, good cohesive strength and heat resistance while also minimizing adhesive melt viscosity. Generally however, these properties cannot be optimized simultaneously. Increasing tack, e.g., by known techniques such as adding increasing amounts of plasticizer oil or liquid resin tackifier, generally decreases strength and heat resistance. On the other hand, increasing strength or heat resistance by increasing polymer content, or by using end-block associating resins generally raises viscosity, or decreases tack, or both. Thus there exists a need for improving cohesive strength without adversely affecting tack, bonding characteristics, heat resistance, or increasing adhesive viscosity.